This renewal proposal seeks continuation of the Training in Developmental Cardiovascular Biology program, initiated 26 years ago. Of the 14 fellows supported by this program during the preceding 10 years who have completed training, 8 have academic appointments at outstanding institutions and all 14 are actively engaged in federally- or privately-funded research programs. This program will continue to utilize the outstanding physiology and molecular and cellular biology laboratories at the Cardiovascular Research Institute and several UCSF departments to train basic scientists who will be at the forefront of developmental cardiovascular research in the coming decades. Modern physiologic and molecular approaches have produced remarkable advances in our knowledge of cardiovascular biology and disease, and the fields of human genetics and stem cell biology are providing still more opportunities. These developments promise rapid scientific progress and underscore the ongoing need for well-trained investigators to both continue this work and build bridges between basic discovery and the advancement of human health. To this end we will: 1) exploit the unique training opportunities in the CVRI, the Department of Pediatrics, and UCSF in general in areas of basic biology;2) recruit graduates of top Ph.D. and M.D.-Ph.D. programs to careers in cardiovascular research;and 3) combine clinical pediatric cardiology training with a rigorous grounding in basic research to facilitate the training of physician-scientists. This grant will support 4 postdoctoral fellows, each for 2 years, and features two tracks. Track I, the newly named Physician-Investigator Pathway, will support M.D. trainees seeking both clinical pediatric cardiology and basic science research training. Trainees in this Track will receive support from this training grant only for the research component of their training. Track II will support Ph.D. or M.D.-Ph.D. trainees who will compete openly for postdoctoral positions in basic cardiovascular biology. A strong didactic curriculum will be provided in a rich scientific environment with rigorous graduate courses, regular trainee meetings, and attentive mentorship. Each trainee will execute a research project with one of the 22 outstanding program faculty preceptors.